We plan to construct an electron spin echo spectrometer operating from 8 to 18 GHz with ancillary equipment for recording and making Fourier transforms of the echo envelope and for the study of the linear electric field effect. The need for such an instrument is based on the lack of reliability of an existing 8-12 GHz spectrometer at Bell Laboratories and the requirement for an instrument operating at 12-18 GHz in order to study the 14N nuclear quadrupolar coupling in paramagnetic biomolecules. In addition, we plan to study the magnetic interaction between unpaired electron spins in paramagnetic metalloproteins and 2H, 13C and 31P nuclei in isotopically labeled substrates and anions that specifically bind to these molecules. Quantitative information from these studies will delineate the number and distance of individual nuclei from paramagnetic centers.